[Tabs] Textarea values not shown in hidden tabs

#### Bug, feature request, or proposal:
The value of text area with mdTextareaAutosize is not visible until the size of the text area is recalculated (with resizeToFitContent() or by typing) when the text area is inside an MdTab that is not initially visible.
The min rows is also not working.

#### What is the expected behavior?
The text area value is visible and min rows works.

#### What is the current behavior?
The text area value is not visible until the value change by typing or resizeToFitContent is called and min rows doesn't works.

#### What are the steps to reproduce?
http://plnkr.co/edit/h4EYvCm36ncKlJolJnhU?p=preview
Open plunker and go to the second tab.

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?
Angular: 4.2.3
Material: 2.0.0-beta.6
Windows 10
Typescript: 2.3.4